Oregon State University Forest Modeling Helps Identify Best Harvesting Rotations for Maximum Carbon Sequestration

Forest modeling by Oregon State University (OSU) scientists shows that a site’s productivity—an indicator of how fast trees grow and how much biomass they accumulate—is the main factor that determines which time period between timber harvests allows for maximum above-ground carbon sequestration.

Originally published in the journal Forests, the findings are important for Pacific Northwest forest managers seeking to strike an optimal balance between harvesting and carbon sequestration, an important tool in fighting climate change.

Forests in the Northwest stretch across nearly 25 million acres and are among the most productive in the world, the authors say, with forests in the Oregon Coast Range boasting especially high biomass and carbon densities thanks to the range’s wet and mild growing conditions.

Over a 240-year projection time frame, the OSU scientists found that for highly productive stands, 60-year rotations with low-intensity thinning at 40 years led to the greatest carbon storage (in the standing trees plus what was removed from the thinning). For stands on less productive sites, they found carbon storage was maximized by rotation periods of 80 years or 120 years.

The study by Catherine Carlisle, Temesgen Hailemariam, and Stephen Fitzgerald of the OSU College of Forestry notes that the carbon trapped in the woody biomass of US forests offsets 13% of the nation’s greenhouse gas emissions. Green plants pull carbon dioxide from the air during photosynthesis, the process through which they use sunlight to make food from carbon dioxide, soil nutrients, and water.